import astropy
from astropy.io import fits
import numpy as np
import warnings
from uvcal import UVCal
import utils as uvutils


def _warn_oldcalfits(filename):
    warnings.warn('{file} appears to be an old calfits format '
                  'which does not fully conform to the FITS standard. '
                  'Setting default values now, set strict_fits=True '
                  'to error rather than warn on this problem, '
                  'rewrite this file with write_calfits to ensure '
                  'FITS compliance.'.format(file=filename))


def _warn_olddelay(filename):
    warnings.warn('{file} appears to be an old calfits format '
                  'for delay files which has been depricated. '
                  'Rewrite this file with write_calfits to ensure '
                  'future compatibility.'.format(file=filename))


class CALFITS(UVCal):
    """
    Defines a calfits-specific class for reading and writing calfits files.
    """

    def write_calfits(self, filename, run_check=True, check_extra=True,
                      run_check_acceptability=True, clobber=False):
        """
        Write the data to a calfits file.

        Args:
            filename: The calfits file to write to.
            run_check: Option to check for the existence and proper shapes of
                parameters before writing the file. Default is True.
            check_extra: Option to check optional parameters as well as required
                ones. Default is True.
            run_check_acceptability: Option to check acceptable range of the values of
                parameters before writing the file. Default is True.
            clobber: Option to overwrite the filename if the file already exists.
                Default is False.
        """
        if run_check:
            self.check(check_extra=check_extra,
                       run_check_acceptability=run_check_acceptability)

        if self.Nfreqs > 1:
            freq_spacing = self.freq_array[0, 1:] - self.freq_array[0, :-1]
            if not np.isclose(np.min(freq_spacing), np.max(freq_spacing),
                              rtol=self._freq_array.tols[0], atol=self._freq_array.tols[1]):
                raise ValueError('The frequencies are not evenly spaced (probably '
                                 'because of a select operation). The calfits format '
                                 'does not support unevenly spaced frequencies.')
            if np.isclose(freq_spacing[0], self.channel_width):
                freq_spacing = self.channel_width
            else:
                rounded_spacing = np.around(freq_spacing, int(np.ceil(np.log10(self._freq_array.tols[1]) * -1)))
                freq_spacing = rounded_spacing[0]
        else:
            freq_spacing = self.channel_width

        if self.Ntimes > 1:
            time_spacing = np.diff(self.time_array)
            if not np.isclose(np.min(time_spacing), np.max(time_spacing),
                              rtol=self._time_array.tols[0], atol=self._time_array.tols[1]):
                raise ValueError('The times are not evenly spaced (probably '
                                 'because of a select operation). The calfits format '
                                 'does not support unevenly spaced times.')
            if np.isclose(time_spacing[0], self.integration_time):
                time_spacing = self.integration_time
            else:
                rounded_spacing = np.around(time_spacing, int(np.ceil(np.log10(self._time_array.tols[1]) * -1)))
                time_spacing = rounded_spacing[0]
        else:
            time_spacing = self.integration_time

        if self.Njones > 1:
            jones_spacing = np.diff(self.jones_array)
            if np.min(jones_spacing) < np.max(jones_spacing):
                raise ValueError('The jones values are not evenly spaced.'
                                 'The calibration fits file format does not'
                                 ' support unevenly spaced polarizations.')
            jones_spacing = jones_spacing[0]
        else:
            jones_spacing = -1

        prihdr = fits.Header()
        if self.total_quality_array is not None:
            totqualhdr = fits.Header()
            totqualhdr['EXTNAME'] = 'TOTQLTY'
        if self.cal_type != 'gain':
            sechdr = fits.Header()
            sechdr['EXTNAME'] = 'FLAGS'
        # Conforming to fits format
        prihdr['SIMPLE'] = True
        prihdr['BITPIX'] = 32
        prihdr['TELESCOP'] = self.telescope_name
        prihdr['GNCONVEN'] = self.gain_convention
        prihdr['CALTYPE'] = self.cal_type
        prihdr['INTTIME'] = self.integration_time
        prihdr['CHWIDTH'] = self.channel_width
        prihdr['XORIENT'] = self.x_orientation
        if self.cal_type == 'delay':
            prihdr['FRQRANGE'] = ','.join(map(str, self.freq_range))
        elif self.freq_range is not None:
            prihdr['FRQRANGE'] = ','.join(map(str, self.freq_range))
        prihdr['TMERANGE'] = ','.join(map(str, self.time_range))
        for line in self.history.splitlines():
            prihdr.add_history(line)

        for p in self.extra():
            ep = getattr(self, p)
            if ep.form is 'str':
                prihdr['{0}'.format(p.upper().replace('_', '')[:8])] = ep.value

        if self.observer:
            prihdr['OBSERVER'] = self.observer
        if self.git_origin_cal:
            prihdr['ORIGCAL'] = self.git_origin_cal
        if self.git_hash_cal:
            prihdr['HASHCAL'] = self.git_hash_cal

        if self.cal_type == 'unknown':
            raise ValueError("unknown calibration type. Do not know how to "
                             "store parameters")

        # Define primary header values
        # Arrays have (column-major) dimensions of [Nimages, Njones, Ntimes, Nfreqs, Nspw, Nantennas]
        # For a "delay"-type calibration, Nfreqs is a shallow axis

        # set the axis for number of arrays
        prihdr['CTYPE1'] = ('Narrays', 'Number of image arrays.')
        prihdr['CUNIT1'] = 'Integer'
        prihdr['CDELT1'] = 1
        prihdr['CRPIX1'] = 1
        prihdr['CRVAL1'] = 1

        # Jones axis
        prihdr['CTYPE2'] = ('JONES', 'Jones matrix array')
        prihdr['CUNIT2'] = ('Integer', 'representative integer for polarization.')
        prihdr['CRPIX2'] = 1
        prihdr['CRVAL2'] = self.jones_array[0]  # always start with first jones.
        prihdr['CDELT2'] = jones_spacing

        # time axis
        prihdr['CTYPE3'] = ('TIME', 'Time axis.')
        prihdr['CUNIT3'] = ('JD', 'Time in julian date format')
        prihdr['CRPIX3'] = 1
        prihdr['CRVAL3'] = self.time_array[0]
        prihdr['CDELT3'] = time_spacing

        # freq axis
        prihdr['CTYPE4'] = ('FREQS', 'Frequency.')
        prihdr['CUNIT4'] = 'Hz'
        prihdr['CRPIX4'] = 1
        prihdr['CRVAL4'] = self.freq_array[0][0]
        prihdr['CDELT4'] = freq_spacing

        # Nspw axis: number of spectral windows
        prihdr['CTYPE5'] = ('NSPWS', 'Number of spectral windows.')
        prihdr['CUNIT5'] = 'Integer'
        prihdr['CRPIX5'] = 1
        prihdr['CRVAL5'] = 1
        prihdr['CDELT5'] = 1

        # antenna axis
        prihdr['CTYPE6'] = ('ANTAXIS', 'See ANTARR in ANTENNA extension for values.')
        prihdr['CUNIT6'] = 'Integer'
        prihdr['CRPIX6'] = 1
        prihdr['CRVAL6'] = 1
        prihdr['CDELT6'] = -1

        # define data section based on calibration type
        if self.cal_type == 'gain':
            if self.input_flag_array is not None:
                pridata = np.concatenate([self.gain_array.real[:, :, :, :, :, np.newaxis],
                                          self.gain_array.imag[:, :, :, :, :, np.newaxis],
                                          self.flag_array[:, :, :, :, :, np.newaxis],
                                          self.input_flag_array[:, :, :, :, :, np.newaxis],
                                          self.quality_array[:, :, :, :, :, np.newaxis]],
                                         axis=-1)
            else:
                pridata = np.concatenate([self.gain_array.real[:, :, :, :, :, np.newaxis],
                                          self.gain_array.imag[:, :, :, :, :, np.newaxis],
                                          self.flag_array[:, :, :, :, :, np.newaxis],
                                          self.quality_array[:, :, :, :, :, np.newaxis]],
                                         axis=-1)

        elif self.cal_type == 'delay':
            pridata = np.concatenate([self.delay_array[:, :, :, :, :, np.newaxis],
                                      self.quality_array[:, :, :, :, :, np.newaxis]],
                                     axis=-1)

            # Set headers for the second hdu containing the flags. Only in cal_type=delay
            # Can't put in pridata because frequency axis is shallow there, but not here
            # Header values are the same as the primary header
            sechdr['CTYPE1'] = ('Narrays', 'Number of image arrays.')
            sechdr['CUNIT1'] = 'Integer'
            sechdr['CRPIX1'] = 1
            sechdr['CRVAL1'] = 1
            sechdr['CDELT1'] = 1

            sechdr['CTYPE2'] = ('JONES', 'Jones matrix array')
            sechdr['CUNIT2'] = ('Integer', 'representative integer for polarization.')
            sechdr['CRPIX2'] = 1
            sechdr['CRVAL2'] = self.jones_array[0]  # always start with first jones.
            sechdr['CDELT2'] = jones_spacing

            sechdr['CTYPE3'] = ('TIME', 'Time axis.')
            sechdr['CUNIT3'] = ('JD', 'Time in julian date format')
            sechdr['CRPIX3'] = 1
            sechdr['CRVAL3'] = self.time_array[0]
            sechdr['CDELT3'] = time_spacing

            sechdr['CTYPE4'] = ('FREQS', 'Valid frequencies to apply delay.')
            sechdr['CUNIT4'] = 'Hz'
            sechdr['CRPIX4'] = 1
            sechdr['CRVAL4'] = self.freq_array[0][0]
            sechdr['CDELT4'] = freq_spacing

            sechdr['CTYPE5'] = ('NSPWS', 'Number of spectral windows.')
            sechdr['CUNIT5'] = 'Integer'
            sechdr['CRPIX5'] = 1
            sechdr['CRVAL5'] = 1
            sechdr['CDELT5'] = 1

            sechdr['CTYPE6'] = ('ANTAXIS', 'See ANTARR in ANTENNA extension for values.')

            # convert from bool to int64; undone on read
            if self.input_flag_array is not None:
                secdata = np.concatenate([self.flag_array.astype(np.int64)[:, :, :, :, :, np.newaxis],
                                          self.input_flag_array.astype(np.int64)[:, :, :, :, :, np.newaxis]],
                                         axis=-1)
            else:
                secdata = self.flag_array.astype(np.int64)[:, :, :, :, :, np.newaxis]

        if self.total_quality_array is not None:
            # Set headers for the hdu containing the total_quality_array
            # No antenna axis, so we have [Njones, Ntime, Nfreq, Nspws]
            totqualhdr['CTYPE1'] = ('JONES', 'Jones matrix array')
            totqualhdr['CUNIT1'] = ('Integer', 'representative integer for polarization.')
            totqualhdr['CRPIX1'] = 1
            totqualhdr['CRVAL1'] = self.jones_array[0]  # always start with first jones.
            totqualhdr['CDELT1'] = jones_spacing

            totqualhdr['CTYPE2'] = ('TIME', 'Time axis.')
            totqualhdr['CUNIT2'] = ('JD', 'Time in julian date format')
            totqualhdr['CRPIX2'] = 1
            totqualhdr['CRVAL2'] = self.time_array[0]
            totqualhdr['CDELT2'] = time_spacing

            totqualhdr['CTYPE3'] = ('FREQS', 'Valid frequencies to apply delay.')
            totqualhdr['CUNIT3'] = 'Hz'
            totqualhdr['CRPIX3'] = 1
            totqualhdr['CRVAL3'] = self.freq_array[0][0]
            totqualhdr['CDELT3'] = freq_spacing

            # Nspws axis: number of spectral windows
            totqualhdr['CTYPE4'] = ('NSPWS', 'Number of spectral windows.')
            totqualhdr['CUNIT4'] = 'Integer'
            totqualhdr['CRPIX4'] = 1
            totqualhdr['CRVAL4'] = 1
            totqualhdr['CDELT4'] = 1
            totqualdata = self.total_quality_array

        # make HDUs
        prihdu = fits.PrimaryHDU(data=pridata, header=prihdr)

        # ant HDU
        col1 = fits.Column(name='ANTNAME', format='8A',
                           array=self.antenna_names)
        col2 = fits.Column(name='ANTINDEX', format='D',
                           array=self.antenna_numbers)
        if self.Nants_data == self.Nants_telescope:
            col3 = fits.Column(name='ANTARR', format='D',
                               array=self.ant_array)
        else:
            # ant_array is shorter than the other columns.
            # Pad the extra rows with -1s. Need to undo on read.
            nants_add = self.Nants_telescope - self.Nants_data
            ant_array_use = np.append(self.ant_array,
                                      np.zeros(nants_add, dtype=np.int) - 1)
            col3 = fits.Column(name='ANTARR', format='D',
                               array=ant_array_use)
        cols = fits.ColDefs([col1, col2, col3])
        ant_hdu = fits.BinTableHDU.from_columns(cols)
        ant_hdu.header['EXTNAME'] = 'ANTENNAS'

        hdulist = fits.HDUList([prihdu, ant_hdu])

        if self.cal_type != 'gain':
            sechdu = fits.ImageHDU(data=secdata, header=sechdr)
            hdulist.append(sechdu)

        if self.total_quality_array is not None:
            totqualhdu = fits.ImageHDU(data=totqualdata, header=totqualhdr)
            hdulist.append(totqualhdu)

        if float(astropy.__version__[0:3]) < 1.3:
            hdulist.writeto(filename, clobber=clobber)
        else:
            hdulist.writeto(filename, overwrite=clobber)

    def read_calfits(self, filename, run_check=True, check_extra=True,
                     run_check_acceptability=True, strict_fits=False):
        """
        Read data from a calfits file.

        Args:
            filename: The calfits file to read to.
            run_check: Option to check for the existence and proper shapes of
                parameters after reading in the file. Default is True.
            check_extra: Option to check optional parameters as well as required
                ones. Default is True.
            run_check_acceptability: Option to check acceptable range of the values of
                parameters after reading in the file. Default is True.
        strict_fits: boolean
            If True, require that the data axes have cooresponding NAXIS, CRVAL,
            CDELT and CRPIX keywords. If False, allow CRPIX to be missing and
            set it equal to zero and allow the CRVAL for the spw directions to
            be missing and set it to zero. This keyword exists to support old
            calfits files that were missing many CRPIX and CRVAL keywords.
            Default is False.
        """
        F = fits.open(filename)
        data = F[0].data
        hdr = F[0].header.copy()
        hdunames = uvutils.fits_indexhdus(F)

        anthdu = F[hdunames['ANTENNAS']]
        self.Nants_telescope = anthdu.header['NAXIS2']
        antdata = anthdu.data
        self.antenna_names = map(str, antdata['ANTNAME'])
        self.antenna_numbers = map(int, antdata['ANTINDEX'])
        self.ant_array = np.array(map(int, antdata['ANTARR']))
        if np.min(self.ant_array) < 0:
            # ant_array was shorter than the other columns, so it was padded with -1s.
            # Remove the padded entries.
            self.ant_array = self.ant_array[np.where(self.ant_array >= 0)[0]]

        self.channel_width = hdr['CHWIDTH']
        self.integration_time = hdr['INTTIME']
        self.telescope_name = hdr['TELESCOP']
        self.history = str(hdr.get('HISTORY', ''))

        if not uvutils.check_history_version(self.history, self.pyuvdata_version_str):
            if self.history.endswith('\n'):
                self.history += self.pyuvdata_version_str
            else:
                self.history += '\n' + self.pyuvdata_version_str

        while 'HISTORY' in hdr.keys():
            hdr.remove('HISTORY')
        self.time_range = map(float, hdr['TMERANGE'].split(','))
        self.gain_convention = hdr['GNCONVEN']
        self.x_orientation = hdr['XORIENT']
        self.cal_type = hdr['CALTYPE']
        if self.cal_type == 'delay':
            self.freq_range = map(float, hdr['FRQRANGE'].split(','))
        else:
            if 'FRQRANGE' in hdr:
                self.freq_range = map(float, hdr['FRQRANGE'].split(','))
        if 'OBSERVER' in hdr:
            self.observer = hdr['OBSERVER']
        if 'ORIGCAL' in hdr:
            self.git_origin_cal = hdr['ORIGCAL']
        if 'HASHCAL' in hdr:
            self.git_hash_cal = hdr['HASHCAL']

        # generate polarization and time array for either cal_type.
        self.Njones = hdr['NAXIS2']
        self.jones_array = uvutils.fits_gethduaxis(F[0], 2, strict_fits=strict_fits)
        self.Ntimes = hdr['NAXIS3']
        self.time_array = uvutils.fits_gethduaxis(F[0], 3, strict_fits=strict_fits)

        # get data.
        if self.cal_type == 'gain':
            self.set_gain()
            self.gain_array = data[:, :, :, :, :, 0] + 1j * data[:, :, :, :, :, 1]
            self.flag_array = data[:, :, :, :, :, 2].astype('bool')
            if hdr['NAXIS1'] == 5:
                self.input_flag_array = data[:, :, :, :, :, 3].astype('bool')
                self.quality_array = data[:, :, :, :, :, 4]
            else:
                self.quality_array = data[:, :, :, :, :, 3]

            self.Nants_data = hdr['NAXIS6']

            self.Nspws = hdr['NAXIS5']
            # add this for backwards compatibility when the spw CRVAL wasn't recorded
            try:
                spw_array = uvutils.fits_gethduaxis(F[0], 5, strict_fits=strict_fits) - 1
                if spw_array[0] == 0:
                    # XXX: backwards compatibility: if array is already (erroneously) zero-
                    #      indexed, do nothing
                    self.spw_array = spw_array
                else:
                    # subtract 1 to be zero-indexed
                    self.spw_array = uvutils.fits_gethduaxis(F[0], 5, strict_fits=strict_fits) - 1
            except(KeyError):
                if not strict_fits:
                    _warn_oldcalfits(filename)
                    self.spw_array = np.array([0])
                else:
                    raise

            # generate frequency array from primary data unit.
            self.Nfreqs = hdr['NAXIS4']
            self.freq_array = uvutils.fits_gethduaxis(F[0], 4, strict_fits=strict_fits)
            self.freq_array.shape = (self.Nspws,) + self.freq_array.shape

        if self.cal_type == 'delay':
            self.set_delay()
            try:
                # delay-style should have the same number of axes as gains
                self.Nants_data = hdr['NAXIS6']
                self.Nspws = hdr['NAXIS5']
                ax_spw = 5
                old_delay = False
            except(KeyError):
                _warn_olddelay(filename)
                self.Nants_data = hdr['NAXIS5']
                self.Nspws = hdr['NAXIS4']
                ax_spw = 4
                old_delay = True

            if old_delay:
                self.delay_array = data[:, :, np.newaxis, :, :, 0]
                self.quality_array = data[:, :, np.newaxis, :, :, 1]
            else:
                self.delay_array = data[:, :, :, :, :, 0]
                self.quality_array = data[:, :, :, :, :, 1]
            sechdu = F[hdunames['FLAGS']]
            flag_data = sechdu.data
            flag_hdr = sechdu.header
            if sechdu.header['NAXIS1'] == 2:
                self.flag_array = flag_data[:, :, :, :, :, 0].astype('bool')
                self.input_flag_array = flag_data[:, :, :, :, :, 1].astype('bool')
            else:
                self.flag_array = flag_data[:, :, :, :, :, 0].astype('bool')

            # add this for backwards compatibility when the spw CRVAL wasn't recorded
            try:
                spw_array = uvutils.fits_gethduaxis(F[0], ax_spw, strict_fits=strict_fits)
                if spw_array[0] == 0:
                    # XXX: backwards compatibility: if array is already (erroneously) zero-
                    #      indexed, do nothing
                    self.spw_array = spw_array
                else:
                    # subtract 1 to be zero-indexed
                    self.spw_array = spw_array - 1
            except(KeyError):
                if not strict_fits:
                    _warn_oldcalfits(filename)
                    self.spw_array = np.array([0])
                else:
                    raise

            # generate frequency array from flag data unit (no freq axis in primary).
            self.Nfreqs = sechdu.header['NAXIS4']
            self.freq_array = uvutils.fits_gethduaxis(sechdu, 4, strict_fits=strict_fits)
            self.freq_array.shape = (self.Nspws,) + self.freq_array.shape

            # add this for backwards compatibility when the spw CRVAL wasn't recorded
            try:
                spw_array = uvutils.fits_gethduaxis(sechdu, 5, strict_fits=strict_fits) - 1
            except(KeyError):
                if not strict_fits:
                    _warn_oldcalfits(filename)
                    spw_array = np.array([0])
                else:
                    raise
            if not np.allclose(spw_array, self.spw_array):
                raise ValueError('Spectral window values are different in FLAGS HDU than in primary HDU')

            time_array = uvutils.fits_gethduaxis(sechdu, 3, strict_fits=strict_fits)
            if not np.allclose(time_array, self.time_array,
                               rtol=self._time_array.tols[0],
                               atol=self._time_array.tols[0]):
                raise ValueError('Time values are different in FLAGS HDU than in primary HDU')

            jones_array = uvutils.fits_gethduaxis(sechdu, 2, strict_fits=strict_fits)
            if not np.allclose(jones_array, self.jones_array,
                               rtol=self._jones_array.tols[0],
                               atol=self._jones_array.tols[0]):
                raise ValueError('Jones values are different in FLAGS HDU than in primary HDU')

        # get total quality array if present
        if 'TOTQLTY' in hdunames:
            totqualhdu = F[hdunames['TOTQLTY']]
            self.total_quality_array = totqualhdu.data

            # add this for backwards compatibility when the spw CRVAL wasn't recorded
            try:
                spw_array = uvutils.fits_gethduaxis(totqualhdu, 4, strict_fits=strict_fits) - 1
            except(KeyError):
                if not strict_fits:
                    _warn_oldcalfits(filename)
                    spw_array = np.array([0])
                else:
                    raise
            if not np.allclose(spw_array, self.spw_array):
                raise ValueError('Spectral window values are different in TOTQLTY HDU than in primary HDU')

            if self.cal_type != 'delay':
                # delay-type files won't have a freq_array
                freq_array = uvutils.fits_gethduaxis(totqualhdu, 3, strict_fits=strict_fits)
                freq_array.shape = (self.Nspws,) + freq_array.shape
                if not np.allclose(freq_array, self.freq_array,
                                   rtol=self._freq_array.tols[0],
                                   atol=self._freq_array.tols[0]):
                    raise ValueError('Frequency values are different in TOTQLTY HDU than in primary HDU')

            time_array = uvutils.fits_gethduaxis(totqualhdu, 2, strict_fits=strict_fits)
            if not np.allclose(time_array, self.time_array,
                               rtol=self._time_array.tols[0],
                               atol=self._time_array.tols[0]):
                raise ValueError('Time values are different in TOTQLTY HDU than in primary HDU')

            jones_array = uvutils.fits_gethduaxis(totqualhdu, 1, strict_fits=strict_fits)
            if not np.allclose(jones_array, self.jones_array,
                               rtol=self._jones_array.tols[0],
                               atol=self._jones_array.tols[0]):
                raise ValueError('Jones values are different in TOTQLTY HDU than in primary HDU')

        else:
            self.total_quality_array = None

        if run_check:
            self.check(check_extra=check_extra,
                       run_check_acceptability=run_check_acceptability)